943 
FXUS65 KMSO 172134
AFDMSO

Area Forecast Discussion
National Weather Service Missoula MT
234 PM MST Sun Jan 17 2021

.DISCUSSION...Persistent snowfall across most of western Montana 
and north central Idaho has gradually begun to lessen this 
afternoon. As expected, this will begin our brief break in snow 
through the rest of this afternoon into this evening. By 
nightfall, our next weak feature will move into western Montana 
under light northerly flow, providing additional light snow across
northwest Montana into west central Montana through Monday 
morning. Accumulations will generally amount to an inch or less 
for valleys, with another 3 to 5 inches possible in terrain above 
4500 feet. The Monday morning commute could be slick as a result 
of lingering snow, so allow for extra time if you are traveling. 
For north central Idaho, snow will likely only impact mountain 
passes crossing the ID/MT border with minor accumulations. As a 
result of the potential for continued travel impacts from snow, 
ongoing Winter Weather Advisories along the Continental Divide 
have been extended through 8 AM MST tomorrow morning.

The weather will then remain fairly quiet through midweek, aside 
from some light mountain snow lingering in the highest terrain of 
western Montana on Wednesday. On Thursday, a low pressure system 
along the Pacific Coast will shift southward, remaining close to 
the coastline, and pull cold Canadian air into the Northern 
Rockies. Confidence remains high that temperatures will start to 
take a nosedive on Friday, but will really be felt Saturday into 
Sunday (and possibly extend into early next week). Overnight low 
temperatures during this time will range in the single digits for 
all of western Montana and much of north central Idaho. Daytime 
highs look to range anywhere from the teens to mid-20s. There is 
the chance that both Max and Min temperatures could be colder than
this, but confidence is low in that occurring at this time. 

Precipitation associated with this push of cold Canadian air is
starting to show up in some of the forecast models, albeit in
modest amounts and with disagreements on the placement of said
moisture. Plenty of other forecast models dig this trough along
the California coast, which would keep the bulk of precip out of
the Northern Rockies. We’ll just have to keep watching as more
details come to light in the coming days to see whether snow
becomes a greater threat. 

&&

.AVIATION...Snowfall continues to decrease and shift southward 
this afternoon, with the main focus currently along and south of 
the Highway 12 corridor. Precipitation will continue to become 
more showery in nature through the afternoon, with periodic 
reductions in visibility and ceiling possible for KGPI, KBTM and 
KSMN. Low stratus and fog will likely linger behind this weather
system, with KGPI and KMSO being the most likely locations to see
ceiling and visibility reductions. Another wave will drop south 
out of Canada tonight, bringing another round of light snow, 
generally along the Continental Divide. KGPI, KMSO and KBTM may 
see brief light snow fall, most likely between 18/06z and 
18/1500z. Widespread obscurations of the terrain should be 
anticipated through Monday morning. 


&&

.MSO WATCHES/WARNINGS/ADVISORIES...
MT...Winter Weather Advisory until 8 AM MST Monday Butte/Blackfoot 
     Region...Potomac/Seeley Lake Region.

     Winter Weather Advisory until 8 AM MST Monday West Glacier 
     Region.

     Winter Weather Advisory until 11 PM MST this evening 
     Bitterroot/Sapphire Mountains.

ID...Winter Weather Advisory until 10 PM PST this evening Southern 
     Clearwater Mountains.

&&

$$